The invention relates to a telecommunications process with time division multiple access (TDMA) between a first and a second station, in which process one station transmits and the other receives in at least one predetermined time slot of a frame.
This process is a telecommunications process with time division multiple access (TDMA) between a first and a second station, in which process one station transmits and the other receives in at least one predetermined time slot of a frame.
In the process with time division multiple access (TDMA), the time axis is subdivided, specifically into frames which are each of the same length and have a predetermined number of bits. For example, each of these frames may be subdivided into an even number of time slots of the same size. The first half of this number of time slots within a frame is used to transmit from the transmitting first station to the receiving second station. This transmission direction is usually referred to as downlink if the first station is a base station and the second station is a mobile station. Accordingly, the second half of the number of time slots within the frame is used to transmit in the opposite transmission direction. Here, the second station transmits while the first station receives. This is usually referred to as uplink if the transmitting station is the mobile station and the receiving station is the base station.
Each of the aforesaid time slots is thus used to set up a transmission channel whose parameters are the number of the time slot within the frame and the carrier frequency used. In order to transmit digital data, the carrier frequency is then frequency-modulated or phase-modulated.
In the European DECT Standard (Digital European Cordless Telecommunications Standard), there are 24 time slots available per frame, specifically 12 in the downlink and 12 in the uplink. In contrast, in the Japanese PHS Standard (Personal Handy Phone System Standard) there are only two times four time slots available per frame, so that the number of time slots per frame is generally not very large.
However, many tasks may require a plurality of transmission channels with different carrier frequencies to be set up. In this case, a plurality of time slots have to be made available per frame in order to carry out the same task, so that, in terms of the number of time slots per frame, a capacity limit is quickly reached. Moreover, if, for reasons of cost, only simple synthesizers are used, the number of usable time slots is reduced further by half since these synthesizers cannot change over from one carrier frequency to another carrier frequency within the very short time period between two time slots.